Re-Pitch on an RIS

Well the RIS I brewed under attenuated and ended up stopping at 1.040 so I am probably going to attempt a repitch with Nottingham or something. Not exactly sure why I got poor attenuation on this beer, it started out at 1.106 and I used 2 properly hydrated packets of US-05 and used pure O2 through a .5 micron difussion stone for aeration, fermented at 65'F.

I have a couple of questions for you guys,

Should I re-aerate and then pitch or just hydrate yeast and pitch? I am probably going to use Nottingham for it's high attenuation properties but I do have US-05 avail if you guys think I should go with this instead. I am really only wanting to pull this beer down to 1.030 or 1.025 so I am not looking for a miracle here, just pull some more points out. I currently have the carboy sitting at around 70'F to try and reactivate the yeast and hopefully eek out a couple of more points.

my thought is that aerating something that has already fermented down so much (more fermentation has taken place than in most beers when they're fully attenuated...) would be risky. I'm sure you want to play it safe with your precious high grav baby. I'd do up a big starter and pitch the slurry.

Have you tried just rousing the yeast a bit? some yeast energizer?

EDIT: it may also be a good idea to acclimate the yeast in a couple of steps to the high alcohol environment.

You are probably done. If you re-pitch you will need a Huge Butt-load of yeast. A stalled big beer will laugh at a re-hydrated pack of dry yeast. A one gallon starters worth of slurry may work, but it also may be done.


What was the recipe? Knowing that may give us an idea of what the problem may be.

You might try a starter of champagne yeast. That's usually good for 18-20% abv and as far as you already are, it shouldn't cause any unusual flavors.
But then again, like niquejim said, you may be done already, depending on your recipe.

if you're really not going to get any more attenuation, you could just oak it for a while, I think that adds a nice palatability to big beers that have lots of sweetness.

Just remember champagne yeast may(probably will) take it to lower than you want

Yeast energizer is a good idea. At the shop where I work we give out instructions for restarting the yeast in case of a stuck fermentation. Draw off a quart of the beer, add a couple of teaspoons of energizer and pitch a pack of yeast. A one gallon glass jug works well for this. Make sure it's in a sanitary container obviously. After it starts fermenting draw off another quart and add it to the actively fermenting beer. Do that twice more so you have a gallon. Then repitch the works back into the main batch. Time consuming, but I haven't had a single person tell me that it didn't work.

Here is the recipe, beersmith calls for 1.028 FG on the fermentables

BeerSmith Recipe Printout - BeerSmith Brewing Software, Recipes, Blog, Wiki and Discussion Forum
Recipe: Imperial Stout
Brewer: biGhuK
Asst Brewer: ziG
Style: Imperial Stout
TYPE: All Grain
Taste: (35.0)

Recipe Specifications
--------------------------
Batch Size: 5.00 gal
Boil Size: 6.84 gal
Estimated OG: 1.112 SG
Estimated Color: 61.6 SRM
Estimated IBU: 106.0 IBU
Brewhouse Efficiency: 72.00 %
Boil Time: 90 Minutes

Ingredients:
------------
Amount Item Type % or IBU
17.50 lb Pale Malt, Maris Otter (3.0 SRM) Grain 81.63 %
1.31 lb Black Barley (Stout) (500.0 SRM) Grain 6.12 %
0.88 lb Special B Malt (180.0 SRM) Grain 4.08 %
0.44 lb Caramunich Malt (56.0 SRM) Grain 2.04 %
0.44 lb Chocolate Malt (350.0 SRM) Grain 2.04 %
0.44 lb Chocolate Malt, Pale (200.0 SRM) Grain 2.04 %
0.44 lb Rye Malt (4.7 SRM) Grain 2.04 %
2.00 oz Warrior [15.00 %] (60 min) Hops 72.3 IBU
1.00 oz Williamette [5.50 %] (10 min) Hops 4.8 IBU
2.00 oz Warrior [15.00 %] (10 min) Hops 26.2 IBU
1.00 oz Williamette [5.50 %] (5 min) Hops 2.6 IBU


Mash Schedule: Single Infusion, Medium Body, Batch Sparge
Total Grain Weight: 21.44 lb
----------------------------
Single Infusion, Medium Body, Batch Sparge
Step Time Name Description Step Temp
60 min Mash In Add 27.87 qt of water at 169.4 F 153.0 F


Notes:
------
Pitch two packets of properly hydrated Safale US-05 and oxygenate wort.

OG was 1.106 at 5 Gallons

Pre Boil OG was 1.072 at 8.5 gallons

Over spaged by 1 gallon, had to boil an extra 20 minutes.

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Oh and I forgot to add but I used 2.2 grams of Wyeast Yeast Nutrient at 15 mins in the boil.